Biomolecules

Updated as of JULY 2020

BIOLOGY

Copyright © 2014-2020 TestBook Edu Solutions Pvt. Ltd.: All rights reserved
 Download Testbook App

Biomolecules
• Chemicals or molecules present in the living organism are called biomolecules.
Biomolecules are divided into two types-

1. Inorganic

2. Organic.

• Inorganic biomolecules includes minerals, gases and water and organic

biomolecules includes carbohydrates, proteins, fats, nucleic acids, vitamins, etc.

• Different biomolecules can be classified as aldehyde, ketones and aromatic

compounds as chemical forms. The amino acids, nucleotides and fatty acids can be
classified as biochemical forms.

Biomolecules

Micromolecules Micromolecules

Minerals Carbohydrates
Gases Lipids
Water Proteins
Sugars Nucleic Acids
Amino acids
nucleotides

Types of Biomolecules

BIOLOGY | Biomolecules PAGE 2

 Download Testbook App

Carbohydrate
• Carbohydrates are made up of carbon, hydrogen, and oxygen.

• There are three types of carbohydrates:-

1) Monosaccharides:- These are

simplest of carbohydrates and are
known as sugars. They are the
building units of complex
carbohydrates. These cannot be
hydrolysed.

2) Oligosaccharides: These consist

of more than one but fewer number
of monosaccharide molecules joined
together by glycosidic bonds. On
hydrolysis, they yield the
monosaccharide units which may be
similar or dissimilar.

3) Polysaccharides: These consist of

a large number of (often thousands)
monosaccharide units to form 1.)
branched or un-branched chains.
These can be hydrolysed to yield
monosaccharide units which are
usually similar.

BIOLOGY | Biomolecules PAGE 3

 Download Testbook App

Proteins
• Proteins are organic nitrogenous compounds in which a large number of amino
acids are joined together by peptide linkages to form long polypeptide chains.

Structure of Proteins
1. Primary structure :- It is the basic structure of protein in which a number of
polypeptides are involved having sequence of amino acids.

• The first amino acid of sequence is called N-terminal amino acid and last
amino acid of peptide chain is called C-terminal amino acid.

2. Secondary structure protein threads forms helix. There are three types of
secondary structure- α helix, β pleated and collagen.

• In α helix, the polypeptide chain is coiled spirally in right handed manner.

• In β pleated secondary proteins two or more polypeptide chains are

interconnected by hydrogen bonds. In collagen there are three strands or
polypeptides coiled around one another by hydrogen bonds.

3. Tertiary structure:- The long protein chain is folded upon itself like a hollow
woollen ball to give three dimensional view of protein.

4. Quaternary structure:- Each polypeptide develops its own tertiary structure and
function as subunit of protein. Eg. Hemoglobin. In adult human hemoglobin 4 sub-
units are involved. The two subunits are of α type and two subunits of β types

BIOLOGY | Biomolecules PAGE 4

 Download Testbook App

Mutarotation

• Mutarotation was discovered by Dubrunfaut in 1844. He noticed that there was a

change in the specific rotation of sugar, in an aqueous solution, with respect to
time.

• It is a deviation from the specific rotation, due to the change in the equilibrium
between α anomeric and β anomeric form, in the aqueous solution.

• For Example:- Mutarotation present in the glucose molecule

Points to Remember

• Glycosidic bonds are covalent chemical bonds that hold together a glycoside. A
glycoside is simply a ring-shaped sugar molecule that is attached to another
molecule.

• A glycosidic bond forms by a condensation reaction, which means that one water
molecule is produced during formation of a glycoside.

BIOLOGY | Biomolecules PAGE 5

 Download Testbook App

Amino Acids

• Amino acids are the building blocks of proteins. There are thousands of amino
acids available in nature, proteins contain only 20 different kinds of amino acids, all
of them are L-alpha-amino acids.
• The same 20 standard amino acids make proteins in all the living cells, may it
either be a virus, yeast, bacteria, plant or human cell.

• These 20 amino acids combine in different sequences and numbers to form

various proteins.

Types of Amino acids - on the basis of charge

1.) Acidic Amino acids :-

Those amino acids that
contain a negative charge or
an acidic group.
For Example :- Aspartic
acid, Glutamic acid

2.) Basic Amino acids:-

Those amino acids that
contain a positive charge or
a basic group.

For Example:- Lysine,

Arginine, Histidine

3.) Neutral Amino acids:-

Those amino acids that do
not contain any charge on
the ‘R’ group

For Example:- Valine,

Glycine, Alanine

BIOLOGY | Biomolecules PAGE 6

 Download Testbook App

Types of Amino acids - on the basis of nutrition

1.) Essential Amino acids:- These amino acids can’t be synthesized in animal body,
and therefore must be present in their diet.

For example, in human being essential amino acids are valine, isoleucine,
phenylalanine, methionine, leucine, lysine, tryptophan and threonine.

2.) Non-essential amino acids:These amino acids can be synthesized in animal

body and may not be supplied in the diet. For example, alanine, arginine, tyrosine,
asparagin, glutamine, proline, etc. In plants all the amino acids are non essential.

For example, in human being essential amino acids are valine, isoleucine,
phenylalanine, methionine, leucine, lysine, tryptophan and threonine.

Memory Tip
• (Remember as VIP, MLL, TT) as sequence for examples of essential amino acids.

BIOLOGY | Biomolecules PAGE 7

 Download Testbook App

Effects of pH and Temperature on proteins

• Each protein shows its highest activity at a particular temperature and pH called the
optimum temperature and optimum pH.

• Activity declines both below and above the optimum value. Low temperature
preserves the enzyme in a temporarily inactive state whereas high temperature
destroys enzymatic activity because proteins are denatured by heat.

Fats
• Fats are a subgroup of compounds known as lipids that are found in the body and
have the general property of being hydrophobic i.e., they are insoluble in water.

• Fats are also termed as triglycerides, molecules made from the combination of one
molecule of glycerol with three fatty acids

• Fatty Acids:-

 A fatty acid has a carboxyl group attached to an R group.

 The R group could be a methyl (–CH3), or ethyl (–C2H5) or higher number of

–CH2 groups (1 carbon to 19 carbons).

BIOLOGY | Biomolecules PAGE 8

 Download Testbook App

• Glycerol:-
 It has three carbon atoms, each of which has a hydroxyl (-OH) group bound
to it.
 It is a simple polyol compound. It is a colourless, odourless, viscous liquid
that is sweet-tasting and non-toxic.

Saturated and unsaturated fatty acids

Basis for
Saturated Fatty acids Unsaturated Fatty acids
comparison

Saturated fatty acids contain single

Unsaturated fatty acids contain carbon
Meaning chain of carbon atoms with no double
chains with one or more double bond.
bond.

Hydrocarbon chain without double Hydrocarbon chain with one or more

Type of Bond
bond (only single bond). double bonds (C=C).

Physical
Solid at room temperature Liquid at room temperature
appearance

Type of chain Straight chain. Bend chains at double bond

Melting point Relatively higher. Relatively lower.

Plant and vegetable oil, avocado,

Sources to
Animal fats, palm oil, coconut oil. sunflower oil, walnuts, flax, canola oil
obtain
and fish oil.

They do not get spoil quickly and are

Shelf life They get spoil quickly
long-lasting

BIOLOGY | Biomolecules PAGE 9

 Download Testbook App

Types of fatty acids

1. Monoglceride:-A monoglyceride is the condensation of one fatty acid and glycerol.

2. Diglyceride:- A diglyceride is the condensation of two fatty acids and glycerol.

3. Triglyceride:- A triglyceride is the condensation of three fatty acids and glycerol.

Points to Remember
• Ester bonds :- In a fat molecule, the fatty acids are attached to each of the three
carbons of the glycerol molecule with an ester bond through the oxygen atom.

• Usually, esters are derived from a carboxylic acid and an alcohol.

BIOLOGY | Biomolecules PAGE 10

 Download Testbook App

DNA and RNA

Deoxyribonucleic Acid
• Deoxyribonucleic acid (DNA) is a
POLYMER OF NUCLEOTIDES
(molecule composed of two chains
made of nucleotides) which coil
around each other io form a double
helix.

• This double helix carries the genetic

instructions used in the growth,
development, functioning and
reproduction of all known living
organisms and many viruses.

• It is found in cell organelles like

Nucleus, Chloroplast, Mitochondria.

• Each nucleotide contains a

phosphate group, a sugar called
deoxyribose and a nitrogen base.

• A nucleotide is composed of one of

four nitrogen-containing nucleobases

• Purine -(guanine [G], adenine [A]).

Pyrimidine-(cytosine [C], or thymine
[T]),

• a sugar called deoxyribose, and a

phosphate group.

• Adenine forms double bond with

Thymine. Cytosine forms triple bond
with Guanine.

BIOLOGY | Biomolecules PAGE 11

 Download Testbook App

DNA Structure
• In 1953, James Watson and Francis Crick discovered the Dna structure.
• The structure of DNA is a double helix Hydrogen strand.
• The nitrogenous bases of the two separate polynucleotide strands are bound
together, according to base pairing rules (A with T and C with G), with hydrogen
bonds to make double-stranded DNA.
• 1 unit of DNA can have a maximum number of 11 nitrogeneous base, but we
cannot determine length of DNA.
• The distance between base pairs is 3.4 Angstroms
• Total Diameter of DNA is 20 Angstroms
• The distance from mid- point to tilt point of DNA is 10 Angstrom.
• The distance of 2 tilt of DNA is 34 Angstrom and width of single DNA thread is 2.8
Angstrom

DNA functions

• DNA stores biological information.

• Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic information
for the development and function of living things. All known cellular life and some
viruses contain DNA.
• It is a biological macromolecule that carries hereditary information in organisms.
• DNA is necessary for the production of proteins, the metabolism, regulation, and
reproduction of the cell.

Major and Minor Grooves

• The major and minor grooves are opposite to each other, and each runs
continuously along the entire length of the DNA molecule.
• The grooves are important in the attachment of DNA Binding Proteins involved in
replication and transcription.
• The major groove occurs where the backbones are far apart, the minor groove
occurs where they are close together.

BIOLOGY | Biomolecules PAGE 12

 Download Testbook App

Reoxyribonucleic Acid

• Ribonucleic acid (RNA) is a

polymeric molecule essential in
various biological roles in coding,
decoding, regulation, and
expression of genes.

• Ribonucleic acid (RNA), unlike

DNA, is usually single-stranded.

• A nucleotide in an RNA chain will

contain ribose (the five-carbon
sugar), one of the four nitrogenous
bases

• (Adenine, Uracil, Guanine, or

Cytosine), and a phosphate group.

• Purine (guanine [G], adenine [A]))

and Pyrimidine (Uracil and cytosine).

Types of RNA

1. Ribosomal ribonucleic acid (rRNA) is the RNA component of the ribosome and is
essential for protein synthesis in all living organisms.

2. T RNA – Transfer RNA

• It is 15 - 20% of total RNA.

• It is stable in nature, and serves as the physical link between the mRNA and the
amino acid sequence of proteins.

BIOLOGY | Biomolecules PAGE 13

 Download Testbook App

3. m - RNA – Messenger RNA

• It is 5-10% of total RNA. It is formed from DNA, and lives for a short period.

• Messenger RNA (mRNA) is a large family of RNA molecules that convey genetic
information from DNA to the ribosome.

• They specify the amino acid sequence of the protein products of gene expression.

• RNA polymerase transcribes primary transcript mRNA (known as pre-mRNA) into

processed, mature mRNA.

Functions of RNA

• RNA does not carry any genetic material.

• The main function of RNA is to carry information of amino acid sequence from the
genes to where proteins are assembled on ribosomes in the cytoplasm.

• DNA makes RNA, and RNA in return makes Protein

• It starts the synthesis of peptide bonds by translating RNA information into protein
information.

BIOLOGY | Biomolecules PAGE 14